var item_left = document.getElementById("item_left");
var item_content = document.getElementById("item_content");
var item_right = document.getElementById("item_right");
var timer;
var itemL = 306; 
var speed = 5;
timer = setInterval(function(){
	speed++;
	item_left.style.left = itemL - speed + "px";
	if(item_left.offsetLeft <= 5){
		item_left.style.left = "0px";
	}
	item_right.style.left = itemL + speed + "px";
	if(item_right.offsetLeft >= 609){
		item_right.style.left = "609px";
		clearInterval(timer);
	}
},1);




